This invention relates to a retainer between a driver's cab and the frame of a vehicle.
Vehicle safety has become an important objective in the design of commercial vehicles. One of the major aspects is the configuration of the retainer between the driver's cab and the frame of the vehicle. An analysis of actual accident history shows that the accidents that require critical attention in the design of a driver's cab and the associated cab support typically involve the rear-ending of another truck. The situation is particularly serious when the frame or chassis systems of the colliding vehicles extend at different levels, since in any such case the energy of the impact is not channeled directly into the frame system of either vehicle but instead strikes the components above and/or below the frame. A direct transfer of the impact energy into the frame system is the exception rather than the rule. A driver's cab takes a particular punishment when the frame, body or trailer platform of the vehicle ahead of it is higher than that of the vehicle behind.
German publication DE 198 31 314 A1 describes a retainer between a driver's cab and the frame of a vehicle that features a spring-loaded base, allowing the driver's cab to tilt. That retainer also includes a connecting element that connects the support to the frame. In that earlier design, the connecting element consists of several components. These include a spring retainer arm and, next to the spring retainer arm, a multi-part restraining element with a longitudinal arm and, connected to it, a swivel bracket. The multi-part restraining element is so designed that in the event of a collision it is deformed in energy-absorbing fashion under maximized retention of the connection between the driver's cab and the frame.
One drawback of that earlier design lies in the complexity of its production and thus its high cost. Several components need to be fabricated and assembled. Moreover, the materials used for the individual components and their shape must be so chosen that, when deformed by an impact, they have the desired energy-absorbing effect and the deformation occurs in the manner intended. To that end, the longitudinal arm is slightly bent toward the top and—viewed from above—uneven. The swivel bracket is provided with specific indentations.
Against that background it is the objective of this invention to introduce a retainer between a driver's cab and the frame of a vehicle that assures optimized occupant safety as well as best possible protection of third parties, while at the same time being inexpensive to make.
Based on the invention, this objective is achieved with a retainer between a driver's cab and the frame of a vehicle incorporating the features claimed.
Accordingly, the invention is characterized by a catch plate having one end which is attached to the connecting element while its other end is attached to the frame. The catch plate constitutes another connection, in addition to the connecting element, between the driver's cab and the frame and, while not exposed to any significant load during normal operation, it serves in a collision to transfer the forces impinging on the driver's cab or its support to the frame, to crumple and to assure a dependable connection between the driver's cab and the frame. In other words, the catch plate moves the cab in controlled fashion until it can no longer prevent an object forcing its way in due to a collision from reaching the engine block. The solution offered by this invention minimizes the risk of a complete separation of the cab from the frame. That translates into enhanced occupant safety as well as reduced potential danger to others since the cab is retained on the frame even after the impact. Moreover, it reduces any potential danger to others.
Another aspect of the invention is the simplicity of producing the catch plate because of its single-part design. A further advantage in terms of cost lies in the fact that the surrounding structure requires only minor modifications since only one additional component, the catch plate itself, needs to be produced and installed.
In one form of implementation, the junction between the catch plate and the frame, as viewed from the front, is located behind a junction between the connecting element and the frame. This has the effect that, after the frame-side connection of the support has failed, the crumpling of the catch plates gives the driver's cab enough room to shift backward. In the process the plates are not exposed to an excessive tensile load but instead they fold along a defined pattern.
In another form of implementation the catch plate is configured in the longitudinal direction in such fashion that, again when viewed from the front, the junction between the catch plate and the frame is closer to the center than the junction between the connecting element and the frame. This again allows the plates to crumple along a particular pattern.
The catch plate may consist for instance of a stamped metal blank, making it easy and inexpensive to produce. It can be die-stamped or bent into the desired shape, obviating in its manufacture the need—unlike cast-metal components—for specially produced molds.
The catch plate may consist of a highly ductile material. The advantage of that is that the material is at once tough and very tractile. These properties are offered for instance by steel type S500MC (steel EN10149, material classification number 1.0984). In the event of an impact, these material properties make for good deformation or crumpling characteristics of the catch plate without exceeding the failure threshold. As a result, the connecting element remains attached to the frame as long as possible, ensuring the retention of the driver's cab on the frame, i.e. the cab is prevented from separating from the frame. Moreover, as the catch plate crumples, it absorbs part of the impact energy, so that only a reduced portion of that energy needs to be transferred into the frame. Simulations have established that about 13% of the original impact energy can be absorbed through the deformation of the catch plate. The actual energy absorption takes place the moment no further rearward shift of the cab is possible or the incoming object has penetrated all the way to the engine block.
The catch plate may be of essentially uniform width over its full length. Its ends may be rounded. The catch plate may be provided with drill holes to accommodate appropriate fasteners. A console may be positioned between the connecting element and the frame. The console serves as an adapter between the support and thus the entire driver's cab and the frame. Its top end accommodates the base, and its bottom end connects to the frame.
The console may consist of a nonductile material with properties such as those of the GGG60 cast metal. The relatively limited tractility of that material has been selected to ensure that the console gives way in the event of a collision.
The console may be connected to the frame at two mutually remote points, one behind the other as viewed from the front. For that purpose the console may have two legs in an inverted V-configuration, converging at the top.
If a console of that type is provided between the connecting element and the frame, the catch plate can extend from the junction between the connecting element and the console all the way to a junction between the console and the frame.
The structural design is particularly simple when the catch plate extends essentially parallel to one of the console legs. This makes it possible to attach the catch plate and the console to the connecting element and, respectively, to the frame using the same fasteners, with an appropriately beneficial effect on the manufacturing cost.
The following will explain this invention in more detail with the aid of the examples illustrated in the attached drawings.